A method for preparing graphene-like based on microalgae cell biomass

Abstract

This invention relates to a method for preparing graphene-like materials based on microalgal cell biomass. The method includes the following steps: (1) pre-activating Spirulina platensis cells, drying the powder, then washing and grinding it; (2) pre-pyrolyzing the Spirulina platensis cell powder ground in step (1), followed by pre-pyrolysis and grinding; (3) secondary activation and pyrolysis of the microalgal cells: mixing the powder product obtained in step (2) with one or more of FeCl2·4H2O, FeCl3·6H2O, CaCl2·2H2O, and ZnCl2 in a mass ratio of 4:1 to 1:10, and performing secondary activation and pyrolysis; (4) post-processing to obtain graphene-like materials. This invention uses Spirulina platensis as biomass raw material and prepares graphene-like carbon materials with different morphologies, specific surface areas, and porosity through a pre-pyrolysis-secondary activation and pyrolysis process.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to a method for preparing graphene-like substances based on microalgae cell biomass. Background Technology

[0002] Graphene, as a carbon atom sp... 2 Two-dimensional carbon nanomaterials with hexagonal honeycomb lattices composed of hybrid orbitals hold significant promise for applications in materials science, energy, and biomedicine due to their excellent optical, electrical, and mechanical properties. Traditional graphene preparation methods, categorized by powder and film, include mechanical exfoliation, redox methods, SiC epitaxial growth, and chemical vapor deposition. Given the limitations imposed by these processes on environmental safety, sustainable development, and yield, designing a novel and efficient preparation method to obtain graphene with superior application performance is of significant research importance and value, considering factors such as cost, safety, and environmental protection of graphene preparation processes and raw materials. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing graphene-like substances based on microalgae cell biomass.

[0004] The technical solution to achieve the objective of this invention is: a method for preparing graphene-like substances based on microalgal cell biomass, comprising the following steps:

[0005] Step (1): Pre-activated Spirulina platensis cells are dried into powder, then washed and ground;

[0006] Step (2): Preheating and decomposing the Spirulina platensis cell powder ground in step (1), followed by grinding;

[0007] Step (3): Secondary activation and pyrolysis of microalgal cells: The powder product obtained in step (2) is mixed with one or more of FeCl2·4H2O, FeCl3·6H2O, CaCl2·2H2O and ZnCl2 in a mass ratio of 4:1-1:10, and then subjected to secondary activation and pyrolysis. The activation and pyrolysis conditions are: a flow rate of 10-50 mL·min -1 Under an Ar atmosphere, the mixed powder was heated in a tube furnace at 2-10 °C / min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate, a carbonization final temperature of 400-900℃, and a holding time of 1-6h.

[0008] Step (4): Post-processing to obtain graphene-like material.

[0009] Further, step (1) specifically involves: preparing a 1-5 wt% dilute hydrochloric acid aqueous solution as a pre-activation activator; mixing the dried powder of Spirulina platensis cells and the activator at a mass ratio of 1:50-1:300; activating at 500 rpm for 10-30 h; after activation, washing the sample with deionized water until neutral and filtering; drying in a vacuum drying oven at 60℃-80℃; and grinding in an agate mortar for 5-15 min to form a powder.

[0010] Furthermore, step (2) specifically involves: processing the powder obtained in step (1) at a flow rate of 10-50 mL / min. -1 Under Ar atmosphere protection, it is placed in a tube furnace at 2-10℃·min -1 The heating rate is set at a final temperature of 300-700℃, and the holding time is 1-6 hours for pre-pyrolysis. After the pyrolysis reaction is completed and cooled, the product is thoroughly ground, washed, dried, and then ground again for 5-15 minutes into powder.

[0011] Further, step (4) specifically involves: washing the powder sample obtained in step (3) thoroughly with deionized water 3-5 times to remove excess impurities, filtering, drying in a vacuum drying oven at a temperature of 60℃-80℃, and grinding it into powder using an agate mortar for 5-15 minutes after drying.

[0012] A graphene-like material prepared using the method described above.

[0013] Compared with the prior art, the significant advantages of this invention are:

[0014] This invention uses microalgae, one of the most common plants in nature, as raw materials to prepare novel graphene carbon materials with special structures through pre-pyrolysis and secondary activation pyrolysis. The microstructure of the products was observed by scanning electron microscopy and transmission electron microscopy, and the composition and properties of the carbon materials were tested by Raman spectroscopy and specific surface area and porosity analyzers. The process is safe, non-toxic and harmless, and the raw materials are widely available and readily available, with the advantage of low cost. It has broad application prospects in composite materials, energy, electrochemistry, biomedicine and other fields.

[0015] This invention selects suitable graphene-driven activators by employing *Spirulina platensis* and its pyrolysis activation mechanism. Through optimization of process parameters such as chemical ratio, heating rate, reaction temperature, and time, a method for preparing graphene-like carbon materials from *Spirulina platensis* cells is finally determined. Compared with existing achievements in preparing porous carbon materials from microalgae biomass, this invention uses *Spirulina platensis* cells with a length of tens to hundreds of micrometers and a width of tens of nanometers as raw materials. Through secondary catalytic pyrolysis activation, the horizontal organic volatilization reduces the size, while the vertical carbon atom pyrolysis strips away the dimensional constraints to obtain graphene-like materials. Attached Figure Description

[0016] Figure 1 An optical microscope image of Spirulina platensis, a preferred algae species for this invention.

[0017] Figure 2 This is a SEM image (10kV, ×50k) of the graphene-like material obtained in Example 1 of this invention.

[0018] Figure 3 This is a SEM image (10kV, ×100k) of the graphene-like material obtained in Example 1 of this invention.

[0019] Figure 4 This is the TEM image of the graphene-like material obtained in Example 1 of this invention.

[0020] Figure 5 This is the TEM image of the graphene-like material obtained in Example 1 of this invention.

[0021] Figure 6 This is a SEM image (10kV, ×10k) of the graphene-like material obtained in Example 2 of this invention.

[0022] Figure 7 This is a SEM image (10kV, ×10k) of the graphene-like material obtained in Example 3 of this invention.

[0023] Figure 8 This is a SEM image (10kV, ×3k) of the biocarbon material obtained in Comparative Example 1 of this invention.

[0024] Figure 9 This is a SEM image (10kV, ×5k) of the biocarbon material obtained in Comparative Example 2 of this invention.

[0025] Figure 10 This is a SEM image (10kV, ×10k) of the biocarbon material obtained in Comparative Example 3 of this invention.

[0026] Figure 11 This is a SEM image (10kV, ×10k) of the activated carbon material obtained in Comparative Example 4 of this invention.

[0027] Figure 12 This is the Raman spectrum (test wavelength 532 nm) of the novel carbon material obtained in Example 1 of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings.

[0029] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0030] A method for preparing graphene-like substances based on Spirulina platensis cell biomass is as follows:

[0031] (1) Prepare a 1-5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:50-1:300 and activate at 500rpm for 10-30h. After activation, wash the sample with deionized water until neutral and filter. Dry it in a vacuum drying oven at 60℃-80℃. After drying, grind it into powder with an agate mortar for 5-15min.

[0032] (2) The powder obtained in step (1) is subjected to a flow rate of 10-50 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 2-10℃·min -1 The heating rate is set at a final temperature of 300-700℃, and the holding time is 1-6 hours for pre-carbonization. After the pyrolysis reaction is completed and cooled, the product is thoroughly ground, washed, dried, and then ground again for 5-15 minutes into powder.

[0033] (3) The powder product obtained in step (2) is thoroughly ground and mixed with one or more of FeCl2·4H2O, FeCl3·6H2O, CaCl2·2H2O, and ZnCl2, with a mass ratio of powder product to reagent of 4:1-1:10, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 10-50 mL·min -1 Under an Ar atmosphere, the mixed powder was heated in a tube furnace at 2-10 °C / min. -1 The activation pyrolysis reaction is carried out under the conditions of a heating rate, a carbonization final temperature of 400-900℃, and a holding time of 1-6h.

[0034] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly with deionized water 3-5 times to remove excess impurities, filter, dry in a vacuum drying oven at a temperature of 60℃-80℃, and grind into powder with an agate mortar for 5-15 minutes after drying.

[0035] Example 1

[0036] A method for preparing graphene-like materials from microalgal cell biomass, the method is as follows:

[0037] (1) Prepare a 2wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:100. Activate at 500 rpm for 30 h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 60°C. After drying, grind into powder using an agate mortar for 8 min.

[0038] (2) The powder obtained in step (1) is subjected to a flow rate of 25 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 6℃·min -1 The heating rate was set at a final temperature of 400℃, and the holding time was 2 hours for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed, dried, and then ground again for 8 minutes to form powder.

[0039] (3) The powder product obtained in step (2) is thoroughly ground and mixed with CaCl2·2H2O, with a mass ratio of powder product to reagent of 1:3, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 25 mL·min -1 Under the protection of an Ar atmosphere, the mixed powder was heated in a tube furnace at 6 °C·min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate of 750℃, a carbonization final temperature of 750℃, and a holding time of 4h.

[0040] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly 5 times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 80°C, and grind into powder with an agate mortar for 9 minutes after drying.

[0041] The carbon material powder prepared in step (4) of this embodiment was observed using a scanning electron microscope (S-4800, Hitachi), and the obtained SEM image is shown below. Figure 2 and 3 As shown, the novel carbon material prepared in Example 1 exhibits a high specific surface area structure with obvious layered wrinkles. The magnified edge image reveals a multi-layered or even single-layer morphology, similar to graphene. Characterization using TEM (JEOL-2100) yielded the following results: Figure 4 and 5 As shown, the carbon material prepared in this embodiment exhibits a distinct sheet-like structure at the nanoscale, with dimensions of approximately several hundred nanometers. The magnified morphology images reveal a two-dimensional nanostructure composed of bilayers or even single layers of carbon atoms. The Raman spectroscopy characterization results are shown below. Figure 12 As shown, the test wavelength was 532nm, and it was clearly observed in the image at 1350cm. -1 and 1588cm -1Two high-intensity characteristic peaks are observed, corresponding to the D and G peaks of graphene carbon materials, respectively. The D peak reflects defects in the carbon atom lattice, while the G peak originates from the stretching vibrations within the sp2 hybridization plane of carbon atoms. This curve is consistent with the trend of graphene material formation through the exfoliation of graphene oxide, and demonstrates the extremely small crystal size of the product. Furthermore, studies typically calculate the ID / IG value to reflect the defects and graphitization degree of carbon materials. The novel carbon material prepared in this embodiment has an ID / IG value of 0.99, compared to the traditional graphite ID / IG value of 0.04, indicating a higher degree of amorphous state and more defects. The above confirms that the process for preparing graphene materials from *Spirulina platensis* involved in this invention is feasible and successful.

[0042] Example 2

[0043] A method for preparing graphene-like substances from microalgal cell biomass, the preparation method is as follows:

[0044] (1) Prepare a 2.5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:120. Activate at 500rpm for 18h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 70℃. After drying, grind in an agate mortar for 10.5min into powder.

[0045] (2) The powder obtained in step (1) is subjected to a flow rate of 50 mL·min. -1 Under an Ar atmosphere of protection, it was placed in a tube furnace at 9.5℃·min -1 The heating rate was set at a final temperature of 700℃, and the holding time was 2 hours for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed, dried, and then ground for another 13 minutes to form a powder.

[0046] (3) The powder product obtained in step (2) is thoroughly ground and mixed with CaCl2·2H2O and ZnCl2, with a mass ratio of powder product to reagent of 3:1, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 35 mL·min -1 Under the protection of an Ar atmosphere, the mixed powder was heated in a tube furnace at 5 °C·min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate of 1.5 h, a carbonization final temperature of 600 °C, and a holding time of 1.5 h.

[0047] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly 5 times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 60°C, and grind into powder using an agate mortar for 12 minutes after drying.

[0048] The carbon material powder prepared in step (4) of this embodiment was observed by scanning electron microscopy, and the obtained SEM image is shown below. Figure 6 As shown, its morphology is a strip-shaped thin sheet structure with a length of 500nm-1μm and a width of 10-30nm, with wrinkles at the edges and a large specific surface area.

[0049] Example 3

[0050] A method for preparing graphene-like substances from microalgal cell biomass, the preparation method is as follows:

[0051] (1) Prepare a 5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:80. Activate at 500 rpm for 20 h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 65°C. After drying, grind in an agate mortar for 12 min to form powder.

[0052] (2) The powder obtained in step (1) is subjected to a flow rate of 20 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 3℃·min -1 The heating rate was set at a final temperature of 350℃, and the holding time was 5.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed, dried, and then ground for another 15 minutes to form powder.

[0053] (3) The powder product obtained in step (2) is thoroughly ground and mixed with ZnCl2 at a mass ratio of 1:1.5, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 48 mL·min⁻¹. -1 Under an Ar atmosphere, the mixed powder was heated in a tube furnace at 9.5 °C / min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate of 1.5 h, a carbonization final temperature of 650 °C, and a holding time of 1.5 h.

[0054] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly 5 times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 65°C, and grind into powder with an agate mortar for 6.5 min after drying.

[0055] The carbon material powder prepared in step (4) of this embodiment was observed by scanning electron microscopy, and the obtained SEM image is shown below. Figure 7 As shown, a large number of graphene-like monolayer morphological structures were observed, and the sheet-like area size was reduced to the scale of several hundred nanometers due to the activation pyrolysis.

[0056] Example 4

[0057] A method for preparing graphene-like substances from microalgal cell biomass, the preparation method is as follows:

[0058] (1) Prepare a 5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:80. Activate at 500 rpm for 20 h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 65°C. After drying, grind in an agate mortar for 12 min to form powder.

[0059] (2) The powder obtained in step (1) is subjected to a flow rate of 20 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 3℃·min -1 The heating rate was set at a final temperature of 350℃, and the holding time was 5.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed, dried, and then ground for another 15 minutes to form powder.

[0060] (3) The powder product obtained in step (2) is thoroughly ground and mixed with ZnCl2 at a mass ratio of 1:1.5, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 48 mL·min⁻¹. -1 Under an Ar atmosphere, the mixed powder was heated in a tube furnace at 9.5 °C / min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate of 1.5 h, a carbonization final temperature of 650 °C, and a holding time of 1.5 h.

[0061] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly 5 times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 65°C, and grind into powder with an agate mortar for 6.5 min after drying.

[0062] Example 5

[0063] A method for preparing graphene-like substances from microalgal cell biomass, the preparation method is as follows:

[0064] (1) Prepare a 4.5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:220. Activate at 500rpm for 26h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 75℃. After drying, grind in an agate mortar for 12min to form powder.

[0065] (2) The powder obtained in step (1) is subjected to a flow rate of 20 mL·min. -1 Under an Ar atmosphere of protection, it was placed in a tube furnace at 7.5℃·min -1The heating rate was set at a final temperature of 450℃, and the holding time was 1.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed, dried, and then ground for another 13 minutes to form powder.

[0066] (3) The powder product obtained in step (2) is thoroughly ground and mixed with FeCl3·6H2O, CaCl2·2H2O and ZnCl2, with a mass ratio of powder product to reagents of 1:8, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 45 mL·min -1 Under an Ar atmosphere, the mixed powder was heated in a tube furnace at 4.5 °C / min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate of 700℃, a carbonization final temperature of 700℃, and a holding time of 4h.

[0067] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly 5 times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 60°C, and grind into powder using an agate mortar for 12 minutes after drying.

[0068] Comparative Example 1

[0069] A method for preparing carbon materials from microalgal cell biomass, the preparation method is as follows:

[0070] (1) Prepare a 1.6wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried yellow algae cell powder and the activator at a mass ratio of 1:120. Activate at 500rpm for 20h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 65℃. After drying, grind in an agate mortar for 6min to form powder.

[0071] (2) The powder obtained in step (1) is subjected to a flow rate of 30 mL·min. -1 Under an Ar atmosphere of protection, it was placed in a tube furnace at 5.5℃·min -1 The heating rate was set at a final temperature of 450℃, and the holding time was 4.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed and dried, and then ground for 11min to obtain a new carbon material product prepared by the pyrolysis of *Alternaria pulverata*.

[0072] The SEM morphology image of the carbon material prepared in this comparative example is shown below. Figure 8 As shown, the carbon material obtained from the pyrolysis of *Phyllostachys edulis* cells retains the original strip-shaped segmental structure of the cells, with a scale of micrometers.

[0073] Comparative Example 2

[0074] A method for preparing carbon materials from microalgal cell biomass, the preparation method is as follows:

[0075] (1) Prepare a 3wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Chlorella cell powder and the activator at a mass ratio of 1:60 and activate at 500 rpm for 10-30 h. After activation, wash the sample with deionized water until neutral and filter. Dry it in a vacuum drying oven at 75°C. After drying, grind it into powder using an agate mortar for 14 min.

[0076] (2) The powder obtained in step (1) is subjected to a flow rate of 20 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 6℃·min -1 The heating rate was set at a final temperature of 350℃, and the holding time was 1.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed and dried, and then ground again for 6 minutes to form powder, thus obtaining a novel carbon material product prepared by the pyrolysis of Chlorella.

[0077] The SEM morphology of the carbon material prepared in this comparative example is shown in the figure below. Figure 9 As shown, the carbon material prepared by pyrolysis of Chlorella cells under the process of this invention has a spherical structure with a diameter of about 8 μm, which also retains the spherical morphology of Chlorella cells of 6-8 μm.

[0078] Comparative Example 3

[0079] A method for preparing carbon materials from microalgal cell biomass, the preparation method is as follows:

[0080] (1) Prepare a 2.5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:250. Activate at 500rpm for 14h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 80℃. After drying, grind into powder using an agate mortar for 8min.

[0081] (2) The powder obtained in step (1) is subjected to a flow rate of 45 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 6℃·min -1 The heating rate was set at a final temperature of 550℃, and the holding time was 1.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed and dried, and then ground for another 10 minutes to form powder, thus obtaining a novel carbon material product prepared by one-step pyrolysis of Spirulina platensis without activation.

[0082] The SEM morphology image of the carbon material prepared in this comparative example is shown below. Figure 10 As shown, the novel unactivated carbon material obtained from Spirulina platensis cells via one-step pyrolysis exhibits a strip-like structure, continuing the... Figure 1The cellular structures shown in the optical microscope images have lengths on the micrometer scale and widths on the micro-nano scale.

[0083] Comparative Example 4

[0084] A method for preparing carbon materials from microalgal cell biomass, the preparation method is as follows:

[0085] (1) Prepare a 3.5wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:120. Activate at 500rpm for 6h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 80℃. After drying, grind in an agate mortar for 8min to form powder.

[0086] (2) The powder obtained in step (1) is subjected to a flow rate of 45 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 6℃·min -1 The heating rate was set at a final temperature of 550℃, and the holding time was 1.5h for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed and dried, and then ground for another 10 minutes to form powder, thus obtaining a novel carbon material product prepared by one-step pyrolysis of Spirulina platensis without activation.

[0087] (3) The powder product obtained in step (2) is thoroughly ground and mixed with FeCl2·4H2O and FeCl3·6H2O at a mass ratio of 5:1, and then subjected to secondary activation pyrolysis. The activation pyrolysis conditions are: a flow rate of 30 mL·min -1 Under the protection of an Ar atmosphere, the mixed powder was heated in a tube furnace at 5 °C·min. -1 The activation pyrolysis reaction was carried out under the conditions of a heating rate of 550℃, a carbonization final temperature of 550℃, and a holding time of 3.5h.

[0088] (4) The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly three times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 75°C, and grind into powder using an agate mortar for 6 minutes after drying.

[0089] The carbon material powder prepared in step (4) of this embodiment was observed by scanning electron microscopy, and the obtained SEM image is shown below. Figure 11 As shown, the morphology of this novel carbon material product is a clustered cauliflower structure, with each cluster having a nanoscale size of less than or equal to 50 nm, making it a nano-activated carbon material.

[0090] Table 1

[0091]

[0092] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing graphene-like materials from microalgal cell biomass, characterized in that, Includes the following steps: Step (1): Prepare a 2wt% dilute hydrochloric acid aqueous solution as a pretreatment activator. Mix the dried Spirulina platensis cell powder and the activator at a mass ratio of 1:

100. Activate at 500 rpm for 30 h. After activation, wash the sample with deionized water until neutral and filter. Dry in a vacuum drying oven at 60°C. After drying, grind into powder using an agate mortar for 8 min. Step (2): The powder obtained in step (1) is subjected to a flow rate of 25 mL·min. -1 Under the protection of Ar atmosphere, it is placed in a tube furnace at 6℃·min -1 The heating rate was set at 400℃, and the holding time was 2 hours for pre-carbonization. After the pyrolysis reaction was completed and cooled, the product was thoroughly ground, washed and dried, and then ground for another 8 minutes to form powder. Step (3): The powder product obtained in step (2) is thoroughly ground and mixed with CaCl2·2H2O, with a mass ratio of powder product to reagent of 1:3, and then subjected to secondary activation pyrolysis; the activation pyrolysis conditions are: a flow rate of 25 mL·min -1 Under the protection of an Ar atmosphere, the mixed powder was heated in a tube furnace at 6 °C·min. -1 The activation pyrolysis reaction was carried out under the following conditions: heating rate, carbonization final temperature of 750℃, and holding time of 4h. Step (4): The post-processing conditions for the sample are as follows: wash the obtained powder sample thoroughly 5 times with deionized water to remove excess impurities, filter, dry in a vacuum drying oven at 80°C, and grind into powder with an agate mortar for 9 minutes after drying.

Images